JP2007098796A - Driving method of liquid droplet ejection head, and liquid droplet ejector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable simplification of wiring, etc. for driving a piezoelectric element without impeding formation of a high image quality and speed-up. <P>SOLUTION: In the liquid droplet ejector, a matrix driving circuit 70 has m×n (4×3) piezoelectric elements Pz<SB>ij</SB>connected in matrix. A gate switch 74 is connected to each piezoelectric element Pz<SB>ij</SB>. A column control signal L<SB>j</SB>which turns on and off the gate switches is input in units of columns. A row signal R<SB>i</SB>changed over to an application state of a voltage V<SB>1</SB>, a GND state and an open state is input to the piezoelectric elements in units of rows. Charging, holding of a charged state, and discharging can be carried out for each piezoelectric element. The piezoelectric element can be driven while a terminal voltage of the piezoelectric element is made equivalent to when a driving waveform changing to 0 v-voltage V<SB>1</SB>-0 v is applied. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a droplet discharge device that discharges droplets of ink or the like, and more particularly to a driving method of the droplet discharge device and a droplet discharge device.

  As the droplet discharge device, there is an ink jet recording device including an ink jet recording head as a droplet discharge head. In addition, some inkjet recording apparatuses use a piezoelectric method in which a piezoelectric element such as a piezoelectric element is used as an actuator in addition to the thermal method.

  In an ink jet recording apparatus using a piezoelectric element, the volume (volume) is changed by expanding or contracting the pressure generating chamber filled with ink by the piezoelectric element, and the pressure generating chamber communicates with the change of the internal pressure due to this change. Some use a so-called drop-on-demand system in which ink droplets are ejected from the tip of the nozzle.

  In general, an ink jet recording head is provided with a switching element for each piezoelectric element, and application / stop of a driving voltage is controlled by turning on / off the switching element to control ejection of ink droplets from a nozzle.

  For this reason, it is necessary to connect a signal line for driving the switching element for each piezoelectric element to the ink jet recording head, and when the number of switching elements for controlling the driving of one piezoelectric element increases, the switching is performed. There are as many signal lines as the number of elements. In addition, as the density of the nozzles increases, the density of the piezoelectric elements increases, making the wiring complicated and wiring work difficult.

  In order to realize droplet diameter modulation (modulation of droplet volume) aiming at high image quality in recent years, it is necessary to simultaneously generate a plurality of drive waveforms, which doubles the number of switching elements, The number of wires between the IC, which is an assembly of switching elements, and the control board increases, and the processing becomes complicated (see, for example, Patent Document 1).

  For wiring from the control board to the switching element IC, a plurality of drive waveforms are sequentially generated within one printing cycle, and an arbitrary drive waveform is selected by controlling the IC to realize droplet diameter modulation. Has been proposed (see, for example, Patent Document 2).

  However, this proposal also requires an independent wiring to each piezoelectric element, and cannot solve the complexity of the wiring between the switching element and the piezoelectric element for high nozzle density and high density. Further, as will be described later, since the drive waveform is long, it is not suitable for high-speed printing.

  On the other hand, as a method for reducing the number of parts and wiring between the piezoelectric element and the switching element, there has been proposed an ink jet printer that divides a plurality of driving elements into a plurality of blocks and drives the piezoelectric elements for each block (for example, (See Patent Document 3).

  Incidentally, in the ink jet recording apparatus, high image quality and high speed are required as in other image recording apparatuses.

  As described above, in an ink jet recording apparatus, printing gradation is performed by performing dot diameter modulation (droplet modulation) for adjusting the amount of ejected droplets by controlling the waveform (driving waveform) of the driving voltage applied to the piezoelectric element. In addition, by increasing the density of the nozzles provided in the ink jet recording head for discharging ink droplets, it is possible to improve the printing speed and improve the image quality.

  However, in a piezoelectric element type ink jet recording apparatus, a drive waveform having a length of several tens of microseconds is required to control pressure fluctuation in the ejector. In the proposal of Patent Document 3, the number of block divisions is limited by the length of the drive waveform that can be generated within the printing cycle. Further, there is a problem that the landing position of the droplet on the recording paper for each block is shifted in accordance with the number of resolution divisions.

In addition, since the drive time (voltage application time) is short in the thermal method, it is possible to drive a plurality of pressure generating elements in a time-sharing manner using the matrix drive method, but in a piezoelectric element such as a piezo element, It is necessary to control the pressure wave in the ejector, and it is difficult to shorten the driving time as compared with the thermal pressure generating element. For this reason, in order to apply a predetermined drive waveform to a plurality of piezoelectric elements within one printing cycle, the number of piezoelectric elements is limited, and a predetermined drive waveform is applied to each of the piezoelectric elements. Therefore, there is a problem that the printing speed is sacrificed and it is difficult to increase the speed.
JP 2002-26102 A Japanese Patent Laid-Open No. 10-193857 JP-A-4-77260

  The present invention has been made in view of the above facts, and proposes a driving method of a piezoelectric element and a droplet discharge device that can simplify wiring and the like without hindering high image quality and high speed. Objective.

  In order to achieve the above object, according to the present invention, a plurality of droplet ejectors that eject droplets from nozzles according to a change in voltage applied to a piezoelectric element are arranged, and droplets are ejected from each droplet ejector. A method for driving a droplet discharge head, comprising: a plurality of switching elements that allow one terminal of a piezoelectric element to be grounded to each of the plurality of piezoelectric elements electrically connected in a matrix form; A column control signal for switching on / off of the element is input in units of columns of the piezoelectric element, and a row signal for switching the other terminal side of the piezoelectric element to an applied state, a ground state, and an open state is applied to the piezoelectric element. The liquid droplets are ejected from the droplet ejector by forming a voltage change between the pair of terminals of the piezoelectric element.

  According to the present invention, the piezoelectric elements to which the switching elements are connected are connected in a matrix form of, for example, m rows × n columns, and the piezoelectric elements are obtained by column control signals in units of columns and row control signals in units of rows. A predetermined voltage can be applied to each of these.

  The piezoelectric element is equivalent to a capacitor on the circuit, and when one terminal is grounded by turning on the switching element, a predetermined voltage is applied to the other terminal by the row control signal. The charged state is maintained by being charged with a voltage and opening at least one of the pair of terminals.

  In addition, the switching element is turned on while the piezoelectric element is charged to a predetermined voltage, and the other terminal is grounded by the row signal, whereby the charge accumulated in the piezoelectric element is discharged.

  By performing such charging and discharging, the terminal voltage of the piezoelectric element becomes equal to that when a substantially trapezoidal driving waveform is applied, and droplets can be ejected by this voltage change.

  That is, in the present invention, by controlling the charging timing and discharging timing of the piezoelectric element by the column control signal and the row control signal, a voltage change equivalent to that when a predetermined driving waveform is applied to the piezoelectric element is given, and this voltage The piezoelectric element is driven by the change.

  Thereby, a plurality of piezoelectric elements can be connected and driven in a matrix form capable of reducing the number of components. At this time, a desired voltage change can be given to each piezoelectric element by the column control signal and the row control signal.

  Therefore, for example, when recording an image by ejecting ink droplets, it is possible to simplify the circuit for driving without lowering the print gradation.

  In the present invention, the column control signal is preferably turned on and off twice or more in each column unit within a predetermined period, and the switching element is turned on and off twice or more within a predetermined period. Thus, a voltage change for one waveform can be given to the piezoelectric element within the period.

  Further, in the present invention, a desired voltage change can be applied to an arbitrary piezoelectric element connected in a matrix form by sequentially switching on and off the column control signal in units of columns and repeating.

  Further, in the present invention, the row control signal is switched from the open state to the ground state, the predetermined voltage application state, or the open state in synchronization with the column control signal, and the open state is maintained after the state is maintained for a predetermined time. It is preferable to switch to. Further, in the present invention, the application state of the predetermined voltage by the row control signal may be switched between a plurality of voltages, whereby not only a preset constant voltage change but also a plurality of stages The voltage change can be given.

  Such a droplet discharge device to which the present invention is applied includes a plurality of droplet ejectors that discharge droplets from nozzles in accordance with voltage signals applied to the piezoelectric elements, and a plurality of piezoelectric elements in a matrix format. A switching element that is provided for each of the plurality of piezoelectric elements so that one terminal of the piezoelectric element can be grounded is controllably connected in units of columns and the other terminal of the piezoelectric element. A matrix circuit for connecting the sides in units of rows of piezoelectric elements, column control means for inputting a column control signal for turning on / off the switching elements in units of columns of the piezoelectric elements to the matrix circuit, and the other of the piezoelectric elements Row control means for inputting a row signal for switching the terminal side between the application state of the predetermined voltage, the ground state and the open state to the matrix circuit in units of rows of piezoelectric elements, and the column Driving control means for driving each of the piezoelectric elements to discharge droplets from the droplet ejector by controlling the output of the column control signal of the control means and the output of the row signal of the row control means; As long as it contains.

  The column control means preferably outputs the column control signal for turning on / off at least twice for each column within a predetermined period, and the column control signal for turning on / off the switching element is output. It is more preferable that the data is output in order in units of columns.

  Thereby, for example, when applied as an ink jet recording apparatus, high-quality image recording is possible without causing a decrease in printing speed.

  The row control means switches the row signal from an open state to a ground state, a predetermined voltage application state, or an open state in synchronization with the column control signal, and maintains the state for a predetermined time. After that, it is preferable to switch to the open state.

  Further, the row control means includes a first switching element capable of outputting a predetermined voltage and a second switching element capable of grounding the output side, and the first and second switching elements are separately provided. A row control signal that is turned on may be input from the drive control means, and includes a third switching element that can output a voltage different from the voltage output by the first switching element, A row control signal for individually turning on the first to third switching elements may be input from the drive control means.

  Further, as the droplet discharge device, the row control unit may output a row signal for changing to the ground state and applying a voltage different from the predetermined voltage, and may be set in advance. It may be possible to apply not only the voltage that is applied, but also a voltage that changes with a predetermined waveform.

  As described above, according to the present invention, the switching elements of the piezoelectric elements connected in a matrix are turned on / off in units of columns, and an open state is given in addition to a predetermined voltage application state and a ground state in units of rows. Thus, for example, when recording an image by ejecting ink droplets, there is an effect that it is possible to simplify the circuit for driving without impairing the print gradation and the print speed.

  As a result, it is possible to reduce the number of components, improve manufacturing efficiency, and suppress manufacturing costs.

Embodiments of the present invention will be described below with reference to the drawings.
[First Embodiment]
FIG. 1 shows a schematic configuration of an ink jet recording apparatus 10 applied as a droplet discharge apparatus to the first embodiment.

  In the ink jet recording apparatus 10, a paper feed tray 14 is provided in the lower part of the housing 12. In this paper feed tray 14, paper 16 as recording media is stacked and accommodated, and the paper 16 accommodated in the paper feed tray 14 is picked up one by one from the uppermost layer by a pickup roll 18. It is.

  The paper 16 taken out from the paper feed tray 14 is transported along a paper feed transport path 22 formed in the housing 12 by a plurality of transport roller pairs 20.

  In the housing 12, an endless transport belt 28 stretched between a drive roll 24 and a driven roll 26 is disposed above the paper feed tray 14. The conveyor belt 28 is moved around by the rotational drive of the drive roll 24.

  A recording head array 30 serving as a droplet discharge head is disposed above the transport belt 28. The recording head array 30 is opposed to the flat portion of the conveyance belt 28 between the drive roll 24 and the driven roll 26, and the opposed region of the recording head array 30 is ejected from which ink droplets are ejected from the recording head array 30. It is an area.

  The paper 16 transported along the transport path 22 is held by the transport belt 28 and transported toward the discharge area. The recording head array 30 ejects ink droplets according to image information at the timing when the paper 16 passes through the ejection area, and attaches the ejected ink droplets to the paper 16, thereby converting the image information on the paper 16. Corresponding image recording is performed.

  Further, in the ink jet recording apparatus 10, the paper 16 is circulated while being held by the transport belt 28, thereby allowing the paper to pass through the discharge region a plurality of times, and so-called multipass image recording is possible.

  A configuration in which the paper 16 is opposed to the discharge region by not being provided with the transport belt 28 and rotating by holding and rotating the paper 16 on the outer periphery of a transport roll formed in a cylindrical or columnar shape, for example. In this case, the interval between the recording head array and the paper 16 is made substantially uniform in the discharge region by, for example, curving the discharge region along the peripheral surface of the transport roller. Just do it.

  The recording head array 30 of the inkjet recording apparatus 10 applied to the present embodiment has an effective image recording area (ink droplet ejection area) equal to or greater than the sheet width that is the length in the direction perpendicular to the conveyance direction of the sheet 16. 4 inkjet recording head units corresponding to four colors of yellow (Y), magenta (M), cyan (C), and black (K) (hereinafter simply referred to as head unit 32). Are arranged along the transport direction. As a result, the inkjet recording apparatus 10 can perform full-color image recording.

  The recording head array 30 is immovable along a direction orthogonal to the conveyance direction, but may be configured to be movable as necessary, and thereby, by multi-pass image recording, higher resolution is achieved. It is possible to perform image recording and prevent a droplet discharge defect from appearing in the recording result. The recording head array 30 is not limited to this, and the recording head array 30 may be moved in the main scanning direction with the width direction of the paper 16 as the main scanning direction.

  An ink tank 34 that stores Y, M, C, and K ink liquids is provided in the housing 12, and a reservoir tank 34 </ b> A corresponding to the ink tank 34 is provided in each head unit 32. . The ink liquid in the ink tank 34 enters the reservoir tank 34A via an ink supply pipe (not shown) in response to the ink liquid in the reservoir tank 34A being ejected from each of the head units 32 toward the paper 16. To be replenished.

  Further, four maintenance units 36 corresponding to the four head units 32 are arranged in the vicinity of the recording head array 30. When performing maintenance of the head unit 32 using the maintenance unit 36, the maintenance unit 36 is moved to a gap formed between the conveyance belt 28 and the recording head array 30, and each of the maintenance units 36 is moved to the head unit 32. It is made to oppose a nozzle surface (surface by the side of the conveyance belt 28).

  In this state, the maintenance unit 36 performs predetermined maintenance operations such as vacuum, dummy jet, wiping, and capping. The maintenance units 36 are divided into two sets of two, and are arranged on the upstream side and the downstream side in the conveyance direction of the paper 16 with the recording head array 30 interposed therebetween.

  In the ink jet recording apparatus 10, a charging roll 38 is provided on the conveyance path 22 side of the recording head array 30 so as to face the conveyance belt 28. The charging roll 38 is driven while sandwiching the paper 16 together with the conveyance belt 28 with the driven roll 26, and between a pressing position where the paper 16 is pressed against the conveyance belt 28 and a separation position separated from the conveyance belt 28. Moved.

  The charging roll 38 is supplied with electric power of a predetermined voltage from a power source (not shown), thereby generating a potential difference with the grounded follower roll 26. The conveying belt 28 is electrostatically adsorbed. The inkjet recording apparatus 10 is provided with a registration roll (not shown) on the upstream side of the charging direction of the paper 16 with respect to the charging roll 38, and the registration of the paper 16 fed between the conveying belt 28 and the charging roll 38 by this registration roll. Is to be done.

  A separation plate 40 is provided on the downstream side of the recording head array 30 in the conveyance direction of the paper 16, and the paper 16 on which an image has been recorded is separated from the conveyance belt 28 by the separation plate 40. A cleaning roll (not shown) that sandwiches the conveyance belt 28 with the driving roll 24 is disposed below the peeling plate 40, and the surface of the conveyance belt 28 from which the paper 16 has been peeled is cleaned. It is cleaned by a roll.

  A paper discharge tray 42 is provided at the top of the housing 12, and a paper discharge conveyance path 44 for conveying the paper 16 toward the paper discharge tray 42 is formed on the downstream side of the peeling plate 40 in the paper conveyance direction. .

  The paper discharge conveyance path 44 includes a plurality of conveyance roller pairs 46, and the paper 16 peeled from the conveyance belt 28 by the peeling plate 40 is conveyed by the conveyance roller pairs 46 and discharged onto the paper discharge tray 42. Collected.

  Further, a reverse conveyance path 50 is formed between the paper feed tray 14 and the conveyance belt 28 by a plurality of conveyance roller pairs 48.

  The sheet 16 on which the image is recorded on one side and sent to the paper discharge transport path 44 is reversed and sent to the paper feed transport path 22 by being sent to the reverse transport path 50. As a result, the inkjet recording apparatus 10 can record images on both sides of the paper 16.

  On the other hand, as shown in FIG. 2, the ink jet recording apparatus 10 is provided with a controller 60 that controls the ejection of ink droplets using the recording head array 30. For example, image data is input to the ink jet recording apparatus 10 from an image processing apparatus such as a personal computer or a workstation, and the controller 60 determines each of the recording head arrays 30 according to the input image data. By controlling the ejection of ink droplets by the head unit 32, image recording corresponding to the image data is performed on the paper 16.

  As described above, the recording head array 30 is longer than the width of the paper 16, and the head units 32 of the respective colors have nozzles that eject ink droplets closely arranged along the width direction of the paper 16. Yes.

  The head unit 32 arranges the nozzles in a plurality of rows such as four rows, for example, and arranges the nozzles in each row two-dimensionally so as not to overlap in the conveyance direction of the paper 16, thereby The nozzles are arranged closely with respect to the direction. Further, the configuration of the droplet discharge head to which the present invention is applied is not limited to this, and any configuration can be applied.

  In the ink jet recording apparatus 10 configured as described above, when image data is input, the paper 16 accommodated and loaded in the paper feed tray 14 passes through the conveyance path 22, the driven roll 26 and the charging roll 38. It is conveyed toward between. When the paper 16 is fed between the driven roll 26 and the charging roll 38, the paper 16 is nipped by the driven roll 26 and the charging roll 38 together with the conveying belt 28, and is held by the conveying belt 28 by being pressed against the conveying belt 28.

  When the paper 16 held on the conveyance belt 28 passes through an ejection region facing the head unit 32 of the recording head array 30 by the circular movement of the conveyance belt 28, ink droplets are generated from the head unit 32 according to image data. By discharging, image recording based on the image data is performed.

  Here, when image recording is performed in only one pass, the paper 16 is peeled off from the transport belt 28 by the peeling plate 40, and the peeled paper 16 is transported along the paper discharge transport path 44 to be discharged from the paper discharge tray 42. To discharge. Also, when performing image recording in multi-pass, the recording belt 16 is passed through the ejection region a plurality of times by moving the conveyor belt 28 in a circular manner, and when the image recording is completed, the recording paper 16 is transferred to the conveyor belt 28. And is discharged to the paper discharge tray 42.

  Incidentally, the head unit 32 is provided with a droplet ejector 64 for ejecting ink droplets. The droplet ejector 64 includes a pressure generating element, a pressure chamber, and a nozzle portion. The droplet ejector 64 employs a piezoelectric element 62 using a piezoelectric element or the like as a pressure generating element provided as an actuator. The piezoelectric element 62 is deformed by an applied voltage, and the droplet ejector 64 A diaphragm forming a part of a wall surface of a pressure chamber (pressure generation chamber) (not shown) is vibrated. The droplet ejector 64 discharges ink droplets in the pressure generation chamber from the nozzles by expanding and contracting the pressure generation chamber by the vibration of the vibration plate.

  As such a droplet ejector 64, a known general configuration using a piezoelectric element 62 can be applied, and detailed description thereof is omitted here. Further, the basic configuration of the Y, M, C, and K head units 32 provided in the recording head array 30 is the same, and the head unit 32 for one color will be described below.

  The controller 60 is provided with a drive control circuit 66 using a drive IC (Integrated Circuit) or the like. The drive control circuit 66 is supplied with power of a predetermined voltage for driving the piezoelectric element 62 from a power supply circuit (not shown).

  The drive control circuit 66 may be provided for each head unit 32 of each color Y, M, C, K, for example, and each may be connected to the controller 60, and each of Y, M, C, K Each color head unit 32 may be connected to one drive control circuit 66.

  The controller 60 outputs a clock signal, print data corresponding to image data, a latch signal, and the like to the drive control circuit 66, and performs power control to be output from the drive control circuit 66 to each piezoelectric element 62 of the head unit 32. Then, the amount of ejected droplets from the nozzles of each droplet ejector 64 of the head unit 32 is controlled to perform image recording on the paper 16 in accordance with the image data.

  On the other hand, the head unit 32 is provided with a drive circuit 68 using a switch IC that forms a transfer gate. In the drive circuit 68, a matrix drive circuit 70 and a row control circuit 72 are formed.

  In this embodiment, m piezoelectric elements 62 are set as one set, and n sets are set as one block, and a large number of piezoelectric elements 62 provided in the head unit 32 are divided into a plurality of blocks. A matrix driving circuit 70 and a row control circuit 72 are provided for each.

  The drive control circuit 66 outputs a predetermined control signal to the matrix drive circuit 70 and the row control circuit 72. Based on the control signal input from the drive control circuit 60 and the control signal input from the row control circuit 72, the matrix drive circuit 70 applies a voltage to be applied to each block (m × n) piezoelectric elements 62. Control.

  As one block at this time, for example, since the nozzles are two-dimensionally arranged in the head unit 32, m rows of nozzles are arranged along the width direction of the paper 16 with respect to the number of columns n. A block can be provided in the width direction of the paper 16 with the corresponding piezoelectric element 62 as one set.

  Here, in this embodiment, as an example, twelve piezoelectric elements 62 having 4 rows × 3 columns (m = 4, n = 3) are defined as one block, and the piezoelectric elements 62 for one block are described as an example. To do.

  The drive control circuit 66 applies a drop-on-demand system in which ink droplets are ejected from the nozzles by giving a predetermined drive waveform to each piezoelectric element 62.

  The piezoelectric element 62 is equivalent to a capacitor. When a predetermined voltage is applied, the piezoelectric element 62 is charged so that the terminal voltage becomes that voltage, and is connected to GND (0 v), thereby accumulating charges. Is discharged, and the terminal voltage becomes 0v. Furthermore, the piezoelectric element 62 is maintained in a charged state by opening at least one terminal while being charged to a predetermined voltage.

  When the piezoelectric element 62 is charged or discharged from the charged state, the droplet ejector 64 vibrates a vibration plate (not shown) in the direction of expansion or contraction of the pressure generation chamber. The ink liquid in the pressure generating chamber is ejected from the nozzles by expansion / contraction. That is, ink droplets are ejected from the nozzles when voltage application to the piezoelectric element 62 is switched from on to off or from off to on.

  In addition, the amount of ejected droplets is changed by repeating ON / OFF or OFF / ON within a printing cycle for one dot (hereinafter simply referred to as a printing cycle), or by changing the applied voltage or ON / OFF timing at ON. Changes.

Here, in the first embodiment, as shown in FIG. 3, the drive voltage (applied voltage) V of the piezoelectric element 62 is set to the voltage V ₁ , and at least within one printing cycle T from the discharge state (0 v). Ink droplets are ejected by turning on / off twice, and by increasing the number of on / off times, the diameter of dots formed within the printing cycle T (1 dot) is increased or stable ejection is possible. It is trying to become.

4A and 4B show a schematic configuration of the matrix drive circuit 70 applied to the present embodiment. Here, twelve piezoelectric elements 62 are shown as piezoelectric elements Pz _ij (where i = 1 to m, j = 1 to n, where i = 1 to 4, j = 1 to 3). Hereinafter, when a specific piezoelectric element 62 is indicated, it is referred to as a piezoelectric element Pz _ij or the like. 4A and 4B show the same circuit. FIG. 4A shows the piezoelectric elements 62 arranged in a straight line, and FIG. 4B shows the piezoelectric elements 62 arranged in a matrix form (matrix). Yes.

In the matrix drive circuit 70, each of the piezoelectric elements 62 (piezoelectric elements Pz _ij ) is provided with a gate switch 74. When the gate switch 74 is turned on, one electrode of the piezoelectric element Pz _ij is grounded (GND). The

The matrix drive circuit 70 is supplied with row signals R _i (R ₁ , R ₂ , R ₃ , R ₄ ) and column control signals L _j (L ₁ , L ₂ , L ₃ ). ing.

The matrix driving circuit 70, it is adapted to the same row signal to the piezoelectric element Pz _ij of the same line R _i is input, and the gate switch 74 to the piezoelectric elements Pz _ij in the same column, the same column control The signal _Li is input.

That is, the row signal R ₁ to the piezoelectric element Pz _11, Pz _12, Pz ₁₃ is inputted, the row signal R ₂ to the piezoelectric element Pz _21, Pz _22, Pz ₂₃ is input, the piezoelectric element Pz _31, Pz _32, Pz ₃₃ row signal R ₃ is, the piezoelectric elements Pz _41, Pz _42, Pz ₄₃ to the row signal R ₄ is input to. Further, the column control signal L ₁ is input as an operation signal to the gate switch 74 of the piezoelectric elements Pz ₁₁ , Pz ₂₁ , Pz ₃₁ , Pz ₄₁ , and the gate switch 74 of the piezoelectric elements Pz ₁₂ , Pz ₂₂ , Pz ₃₂ , Pz ₄₂ is input. The column control signal L ₂ is input as an operation signal, and the column control signal L ₃ is input as an operation signal to the gate switches 74 of the piezoelectric elements Pz ₁₃ , Pz ₂₃ , Pz ₃₃ , Pz ₄₃ .

Thus, the matrix driving circuit 70, the piezoelectric element Pz _ij are connected in a matrix (matrix form), which enables the matrix driving of the piezoelectric elements Pz _ij due row signal R _i and the column control signal L _j.

On the other hand, FIG. 5 shows an example of the row control circuit 72. In the row control circuit 72, a switch circuit 76 is formed for each row signal R _i input to the matrix drive circuit 70. Each of the switch circuits 76 is formed by two gate switches 78A and 78B.

The gate switches 78A and 78B have one terminal as an input terminal and the other terminal as an output terminal. The gate switch 78A has a voltage V ₁ for driving the piezoelectric element Pz _ij input to the input terminal. The input terminal of the gate switch 78B is grounded (GND).

As a result, the switch circuit 76 outputs the voltage V ₁ as the row signal R _i when the gate switch 78A is turned on, and sets 0v (GND) as the row signal R _i when the gate switch 78B is turned on. Output. Further, the switch circuit 78 can be in a no-signal state in which the output side is opened as the row signal R _i by turning off the gate switches 78A and 78B.

The switch circuit 76 receives row control signals R _i1 and R _i2 at input terminals of the gate switches 78A and 78B. The switch circuit 76 uses the row control signals R _i1 and R _i2 to switch the gate switch. 78A, 78B are turned on / off, as the row signal R _i, and outputs a voltage V _1, GND and open (no signal). Incidentally, the row control signal R _i1, R _i2 has a pulse signal never simultaneously turned on.

In the matrix drive circuit 70 shown in FIGS. 4A and 4B, when the voltage V ₁ is input as the row signal R _i , the gate switch 74 is turned on by the column control signal L _j , whereby the piezoelectric element Pz _ij (Piezoelectric element 62) is charged by applying drive voltage V ₁ and when 0v (GND) is input as row signal R _i , gate switch 74 is turned on, so that the applied voltage becomes 0v. Become (GND).

Further, in the matrix drive circuit 70, the gate switch 74 is turned off or the row control circuit 72 (see FIG. 5) in a state where the piezoelectric element Pz _ij is charged to the voltage V ₁ or in a GND state (discharge state). When the gate switches 78A and 78B are turned off and opened, the voltage V ₁ is held in a charged state or a grounded potential state.

That is, in the matrix driving circuit 70, the row signal R _i and the column control signal L _j, the applied voltage of the piezoelectric element Pz _ij "0v voltages V ₁ from (GND)", "holding voltages V _1", "Voltage V ₁ to 0 v (GND, discharge) ”and“ 0 v (GND) hold ”can be changed, and thereby, the voltage change based on the drive waveform shown in FIG. equivalent state, so that can be generated between the piezoelectric elements Pz _ij terminal.

Further, in the matrix drive circuit 70, the drive voltage (applied voltage) GND is applied to each of the m × n (here, 4 × 3) piezoelectric elements 62 by the combination of the row signal R _i and the column control signal L _j. (0 v) change in ~ voltages V ₁ (charged) and, and can change from voltages V ₁ to GND (0 v) (discharge).

FIG. 6 shows a state change of each piezoelectric element Pz _ij according to the row signal R _i and the column control signal L _j in the matrix drive circuit 70. In FIG. 6, an open state is no line signal R _i - are represented by "".

That is, the voltage application state to the piezoelectric element Pz _ij is individually switched by switching the row signals R _{1 to} R ₄ while inputting the pulse signals that are sequentially turned on as the column control signal L _j to the matrix driving circuit 70. Can do.

As a result, the row signal R _i for driving each piezoelectric element Pz _ij according to the image data, that is, the row control signals R _i1 and R _i2 are input to the row control circuit 72, whereby the image recording according to the image data is performed. Is possible.

Here, an example of the drive signal of the piezoelectric element 62 (Pz _ij ) with respect to the input signal of the matrix drive circuit 70 applied to the first embodiment will be described with reference to FIG.

FIG. 7A shows an example of the column control signal L _j (L _{1 to} L ₃ ) input to the matrix driving circuit 70. As the column control signal L _j , for example, a pulse signal having a pulse width (on time) t of 1 μsec is used, and the pulse signals are sequentially turned on / off.

At this time, even when the pulse width t is 3 μsec, when printing is performed using 4 × 3 piezoelectric elements 62, image recording with a resolution of 600 dpi or more can be performed. Incidentally, the pulse width t, such that a sufficient time for charging and discharging of the piezoelectric elements Pz _ij, is configured with an charging characteristics and discharge characteristics of the piezoelectric element Pz _ij. Also. The column control signals L ₁ , L ₂ , and L ₃ have their on / off timing controlled so that the on states do not overlap.

The controller 60 GNDs the piezoelectric element Pz _ij by the column control signal L _j and the row signal R _i input to the matrix driving circuit 70 at the start timing of each printing cycle T, and the terminal voltage (applied voltage) becomes 0v. In this state, the row control signals R _i1 and R _i2 and the column control signal L _j output from the drive control circuit 66 are controlled so that a drive waveform is output with this state as an initial state.

On the other hand, the row control signals R _i1 and R _i2 are output based on image data to be printed in synchronization with the column control signal L _j .

Here, as shown in FIG. 7C, when the piezoelectric element Pz _i1 (Pz ₁₁ , Pz ₂₁ , Pz ₃₁ , Pz ₄₁ ) is driven, as shown in FIG. 7B, the column control signal L By outputting the row control signals R _i1 and R _i2 so that the row signal R _i becomes the voltage V ₁ at the timing when ₁ is turned on, the piezoelectric element Pz _ij is charged to the voltage V _1. Thereafter, at the timing when the column control signal L ₁ is turned off, the row control signals R _i1 and R _i2 are output so that the row signal R _i is turned off (opened), whereby the terminal voltage (applied voltage) of the piezoelectric element Pz _ij Is held at the voltage V ₁ .

When the applied voltage of the piezoelectric element Pz _ij is lowered from the voltage V ₁ to 0 v, the row control signal R _i1 , so that the row signal R _i becomes 0 v (GND) at the timing when the column control signal L ₁ is turned on. R _i2 is output so that the piezoelectric element Pz _ij is discharged, and then the row control signal R _i1 , so that the row signal R _i is turned off (opened) at the timing when the column control signal L ₁ is turned off. By outputting R _i2 , the terminal voltage (applied voltage) of the piezoelectric element Pz _ij is held at 0 v (GND).

As a result, a single drive waveform that changes from GND to voltages V _{1 to} GND can be obtained for Pz _i1 in the piezoelectric element Pz _ij . That is, the piezoelectric element Pz _i1 is charged by the row signal R _i becoming the voltage V ₁ when the column control signal L ₁ is turned on, and the column control signal L ₁ is turned off or the row signal R _i is turned off. The state charged to the voltage V ₁ is maintained.

In this state, when the column control signal L ₁ is turned on, the row signal R _i becomes GND, whereby the piezoelectric element Pz _i1 is discharged so that the terminal voltage becomes 0 v (GND). .

At this time, the time during which the voltage V ₁ is held can be selected according to the timing at which the row signal R _i is GND.

Further, the same applies to the piezoelectric element Pz _i2 (Pz ₁₂ , Pz ₂₂ , Pz ₃₂ , Pz ₄₂ ) and the piezoelectric element Pz _i3 (Pz ₁₃ , Pz ₂₃ , Pz ₃₃ , Pz ₄₃ ). Can be changed from GND to voltage V _{1 to} GND.

In the piezoelectric element Pz _ij , the change in the terminal voltage is repeated at a predetermined timing, so that a state equivalent to that when a drive waveform corresponding to the change in the terminal voltage is applied is obtained. Ink droplets corresponding to the drive waveform are ejected from the nozzles.

On the other hand, in FIG. 8, as a specific example, drive waveforms are individually applied to the piezoelectric element Pz ₁₁ , the piezoelectric element Pz ₂₂ , the piezoelectric element Pz ₃₂ , and the piezoelectric element Pz ₄₃ in the piezoelectric element Pz _ij , and the other piezoelectric elements. The column control signal L _j and the row control signals R _i1 and R _i2 (row signal R _i ) when the drive of the element Pz _ij is stopped (application of the drive waveform is stopped) are shown.

Further, in FIG. 9, in obtaining a driving waveform of FIG. 8 (C), the row signal R _i and for the column control signal L _j, the piezoelectric element based on the column control signal L _j and the row signal R _i in this case A change in state of the voltage applied to Pz _ij is shown.

Also at this time, for example, when the voltage applied to the piezoelectric element Pz ₁₁ is changed from GND to voltage V _{1 to} GND, the row signal R ₁ is set to the voltage V ₁ in accordance with the on timing of the column control signal L _1. Thus, the row control signal R ₁₁ is turned off and the row control signal R ₁₂ is turned on. As a result, the voltage applied to the piezoelectric element Pz ₁₁ is increased from 0 v (GND) to the voltage V ₁ .

Further, in a state where the piezoelectric element Pz ₁₁ is charged to the voltage V ₁ , the row control signal R ₁₁ is turned on so that the row signal R ₁ becomes GND in accordance with the ON timing of the column control signal L _1. By turning off the control signal R ₁₂ , the piezoelectric element Pz ₁₁ can be discharged, and the applied voltage can be lowered from the voltage V ₁ to 0 v (GND).

The droplet ejector 64 ejects ink droplets by repeatedly changing the applied voltage of the piezoelectric element Pz _ij from GND to voltages V _{1 to} GND. Further, the amount of ejected droplets when forming one dot is adjusted by the number of driving waveforms applied within the printing cycle T.

  In this manner, the matrix driving circuit 70 can be used to individually drive (m × n) piezoelectric elements 62 and to control the amount of droplets ejected from the corresponding droplet ejector 64. Can do.

In other words, by driving the piezoelectric element Pz _ij using only the rising and falling parts of the original driving waveform, the m × n one block of piezoelectric elements Pz _ij is transformed into a matrix. It can be individually driven by the drive circuit 70.

  In the first embodiment, when the (m × n) piezoelectric elements 62 are driven, the head unit 32 is provided with m column control lines and (n × 2) row control lines. Although wiring is required, the number of wirings required can be reduced as compared with the case where the drive waveform and the on / off signal of the gate switch 74 are input for each piezoelectric element 62. Further, the drive circuit 68 provided in the head unit 32 can be simplified and the number of assembly steps can be reduced.

  FIGS. 10A to 10C schematically show the manufacturing process of the head unit 32 according to the first embodiment. Here, one module when the head unit 32 is divided and formed into a plurality of head unit modules is shown and described, but the shape of the head unit 32 to which the present invention is applied and the nozzle arrangement are limited. It is not a thing. Moreover, the material of each member can apply a well-known material, and detailed description is abbreviate | omitted here.

  When manufacturing the head unit 32, first, as shown in FIG. 10A, a thin film semiconductor circuit 82 is formed on the insulating substrate 80 by a low pressure CVD method or the like.

  Next, a piezoelectric element module 84 capable of forming a plurality of piezoelectric elements 62 is mounted on the insulating substrate 80. At this time, the piezoelectric element module 84 is arranged with spherical solder between the insulating substrate 80 and is electrically connected to the thin film semiconductor circuit 82 already formed on the insulating substrate 80 by reflow.

  Thereafter, the piezoelectric element module 84 is aligned by polishing the end face of each piezoelectric element 62 to be mounted. Further, by dicing the end face of the polished piezoelectric element 62, the piezoelectric element 62 is individualized so as to correspond to each pressure generating chamber for each droplet module 64 (not shown) as a minimum structural unit.

  Next, as shown in FIG. 10C, the head main body 86 is mounted. The head main body 86 includes a vibration plate 88, a pressure chamber forming member 90 in which a pressure generating chamber for each droplet ejector 64 is formed, and a nozzle in which a nozzle 92 corresponding to the pressure generating chamber (droplet ejector 64) is formed. Plates 94 are stacked.

  When the head unit 32 is manufactured in this way, the column control wiring 96 is connected to the insulating substrate 80 as shown in FIG. Further, the head main body 86 is manufactured by connecting the wiring 98 for row control to the diaphragm 88. As the wirings 96 and 98, FFC (flexible flat cable) or the like is used.

  In the head array 32 manufactured as described above, the matrix drive circuit 70 is formed by the thin film semiconductor circuit 82, whereby the wiring 96 connected to the insulating substrate 80 can be made common for each column. Further, the wiring 68 connected to the vibrating body 88 can be shared for each row.

  Thereby, the wiring connected to the head unit 32 can be simplified, and the number of components can be reduced, the manufacturing yield can be improved, and the manufacturing cost can be reduced.

In the first embodiment, the row control circuit 72 is provided in the head unit 32. However, by providing the row control circuit 72 in the drive control circuit, the row control circuit 72 is provided between the head unit 32 and the drive control circuit 66. The wiring can be simplified.
[Second Embodiment]
Next, a second embodiment of the present invention will be described. The basic configuration of the second embodiment is the same as that of the first embodiment described above, and in the second embodiment, the same components as those of the first embodiment are the same. Reference numerals are assigned and description thereof is omitted.

In the first embodiment described above, the piezoelectric element 62 (piezoelectric element Pz _ij ) is driven with the drive waveform of the voltage V _1. However, in the second embodiment, 0 v (GND) and the voltage V ₁ are driven. And driving with a driving waveform that changes at three levels of voltage V ₂ (V ₂ > V ₁ ).

That is, driving of the piezoelectric element 62 using the driving waveform of the voltage V _{2 and} the driving waveform of the voltage V ₁ shown in FIG. 11A, and driving with the voltages V ₁ and V ₂ as shown in FIG. The ejection droplet amount is controlled by driving with the voltage V ₁ at the time of.

  FIG. 12 shows a schematic configuration of the row control circuit 100 applied in the second embodiment in place of the row control circuit 72.

The row control circuit 100 is supplied with voltages V ₁ , GND and voltage V ₂ to each switch circuit 76A. The switch circuit 76A has a gate switch 78A for voltage V ₁ and a GND. In addition to the gate switch 78B, a gate switch 78C for the voltage V ₂ is provided.

In addition to the operation signals for the gate switches 78A and 78B, the operation signal for the gate switch 78C is input to each switch circuit 76A. Here, it is assumed that the operation signal of the gate switch 78B is the row control signal R _i1 , the operation signal of the gate switch 78A is the row control signal R _i2 , and the operation signal of the gate switch 78C is the row control signal R _i3 .

As a result, the switch circuit 76A outputs the voltage V ₂ , the voltage V ₁ , GND, or the open row signal R _i based on the row control signals R _{i1 to} R _i3 . At this time, the drive control circuit 66 outputs the row control signals R _{i1 to} R _i3 according to the column control signal L _j as the synchronization signal and the image data.

FIGS. 13 to 15 show an example of driving the piezoelectric element Pz _ij when such a row control circuit 100 and the matrix drive circuit 70 are used. 13 to 15 output the driving waveform shown in FIG. 15, and FIG. 13 shows a row signal R _i based on the column control signal L _j and the row control signals R _{i1 to} R _i3 at this time. FIG. 14 shows a voltage application state to each piezoelectric element 62 (Pz _ij ) based on the column control signal L _j and the row signal R _i in FIG.

As shown in FIG. 13, the column control signal L _j turns on the column control signals L ₁ , L ₂ and L ₃ in order with a predetermined pulse width t. At the start of printing, the drive control circuit 66 sets the piezoelectric element Pz _ij to GND and sets the terminal voltage to 0 v, and then the row control signals R _{i1 to} R _i3 (row signal R _i ) and the column control signal L _j . Start output.

Here, when the applied voltage of the piezoelectric element Pz ₁₁ is increased from 0 v (GND) to the voltage V ₂ , the voltage V ₂ is generated as the row signal R ₁ in accordance with the ON timing of the column control signal L ₁ . That is, the row control signals R ₁₁ and R ₁₂ are turned off and the row control signal R ₁₃ is turned on.

As a result, the voltage V ₂ is output as the row signal R ₁ , and the piezoelectric element Pz ₁₁ is charged to the voltage V ₂ because the column control signal L ₁ is turned on. In this state, by turning off the column control signal L ₁ and the row control signals R ₁₁ , R ₁₂ , and R ₁₃ , the terminal voltage of the piezoelectric element Pz ₁₁ is held at the voltage V ₂ .

Further, in a state where the terminal voltage is held at the voltage V ₂ , the row control signals R ₁₂ and R ₁₃ are turned off and the row control signal R ₁₁ is turned on in accordance with the on timing of the column control signal L _1. By grounding the signal R ₁ , the terminal voltage of the piezoelectric element Pz ₁₁ is lowered from the voltage V ₂ and is grounded.

Thereby, it is possible to obtain a drive waveform that changes from GND to voltage V _{2 to} GND with respect to the piezoelectric element Pz ₁₁ .

Further, when the applied voltage of the piezoelectric element Pz ₁₁ is increased from 0 v (GND) to the voltage V ₁ , the row signal R ₁ is set to the voltage V ₁ in accordance with the ON timing of the column control signal L ₁ . The row control signals R ₁₁ and R ₁₃ are turned off and the row control signal R ₁₂ is turned on.

As a result, the voltage V ₁ is output as the row signal R ₁ and the column control signal L ₁ is turned on, so that the voltage V ₁ is applied to the piezoelectric element Pz ₁₁ to be charged, and the terminal voltage becomes the voltage V ₁ . Be raised. In this state, by turning off the column control signal L ₁ and the row control signals R ₁₁ , R ₁₂ and R ₁₃ , the terminal voltage is held at the voltage V ₁ in the piezoelectric element Pz ₁₁ , and further, the column control signal L ₁ When the row control signals R ₁₂ and R ₁₃ are turned off, the row control signal R ₁₁ is turned on, and the row signal R ₁ is grounded in accordance with the ON timing, the terminal voltage is lowered from the voltage V ₁ and grounded. The

As a result, a drive waveform that changes from GND to voltage V ₁ to GND can be obtained with respect to the piezoelectric element Pz ₁₁ , and the row control signals R ₁₁ , R ₁₂ , and R ₁₃ are turned off in the GND state. Thus, the applied voltage of the piezoelectric element Pz ₁₁ is held at 0 V (GND).

Such voltage application to the piezoelectric element Pz ₁₁ can be similarly applied to each of the piezoelectric elements Pz _ij , and thereby, the row signal R _j (see FIG. 13 (FIG. 13 (B)) shown in FIGS. The applied voltage of each piezoelectric element Pz _ij shown in FIG. 15 can be obtained by the row control signals R _{i1 to} R _i3 ) and the column control signal L _j shown in B).

Thereby, even when the piezoelectric element 62 (Pz _ij ) is driven in a matrix, high gradation can be obtained and high-quality image recording can be performed. At this time, since (m × n) piezoelectric elements 62 are controlled in units of rows and columns, the number of wirings necessary for the control can be reduced and the wiring can be simplified.

On the other hand, in the first and second embodiments, a preset constant voltage (voltage V ₁ or voltages V ₁ and V ₂ ) is applied to the piezoelectric element. It is also possible to apply a changed voltage or voltage waveform.

  FIG. 16 shows an example of a row control circuit (here, referred to as a row control circuit 100A) used when a predetermined drive waveform (voltage waveform) is applied via the matrix drive circuit 70.

The basic configuration of the row control circuit 100A is the same as that of the row control circuit 100 described above, but the drive waveforms A, B, and C are input to the switch circuits 76A in place of the voltages V ₁ , V _2, and GND. Is done. As the drive waveforms A to C, any voltage or voltage waveform can be applied as long as a droplet can be ejected from the droplet ejector 64 using the piezoelectric element 62 (Pz _ij ).

Here, for example, by turning on only the row control signal R _i1, the voltage of the drive waveform A can be applied to the piezoelectric element Pz _ij, and driving by turning on only the row control signal R _i2. The voltage of waveform B can be applied, and the voltage of drive waveform C can be applied by turning on only row control signal R _i3 .

Accordingly, even when m × n piezoelectric elements Pz _ij are driven as one block by the matrix driving circuit 70, the piezoelectric element 62 (Pz _ij ) driving using an arbitrarily set voltage or voltage waveform (voltage change) is performed. Therefore, the gradation can be improved.

  The present embodiment described above shows an example of the present invention and does not limit the configuration of the present invention. For example, in the present embodiment, the inkjet recording apparatus 10 has been described as an example. However, the present invention is not limited to this, and may be applied to an inkjet recording apparatus having an arbitrary configuration that ejects ink droplets using a piezoelectric element. Is possible.

In this embodiment, the column control signal L _j is used as a synchronization signal to drive the piezoelectric element Pz _ij according to the image data as a row signal R _i (row control signal R _i1 , R _i2 or row control signal R _i1. , R _i2 , R _i3 ), but it is also possible to drive the piezoelectric element Pz _ij according to the image data by the column control signal L _i using the row signal R _i as a synchronization signal.

  Furthermore, in the present embodiment, an example of an ink jet recording apparatus that performs image recording by ejecting ink droplets as the liquid droplet ejecting apparatus has been described. However, the present invention is not limited thereto, and a piezoelectric element such as a piezoelectric element is used as an actuator. The present invention can be applied to a droplet discharge apparatus having an arbitrary configuration that discharges droplets by using the.

1 is a schematic configuration diagram of an ink jet recording apparatus according to the present embodiment; It is a schematic block diagram of discharge control of an ink droplet. It is a diagram which shows the outline of the drive waveform of the piezoelectric element which concerns on 1st Embodiment. It is a schematic circuit diagram which shows the matrix drive circuit based on this Embodiment. It is a schematic circuit diagram of the matrix drive circuit equivalent to FIG. 4A. 1 is a schematic circuit diagram showing an example of a row control circuit according to a first embodiment. FIG. It is a graph which shows the state of the applied voltage of the piezoelectric element according to the column control signal and row signal using the matrix drive circuit which concerns on 1st Embodiment. (A) is a timing chart showing an example of a column control signal, (B) is a timing chart showing an example of a row control signal and a row signal corresponding to the row control signal, and (C) is based on (A) and (B). 6 is a timing chart showing a change (drive waveform) of a terminal voltage of the piezoelectric element. (A) is a timing chart showing an example of a column control signal, (B) is a timing chart showing another example of a row control signal and a row signal corresponding to the row control signal, and (C) is (A) and (B). 5 is a timing chart showing a change (drive waveform) of the terminal voltage of the piezoelectric element based on the above. FIG. 9 is a chart showing states of applied voltages of piezoelectric elements corresponding to column control signals and row signals equivalent to those in FIGS. (A), (B), (C) is the schematic which shows the flow of the manufacturing process of a head unit in the order. (A) And (B) is a diagram which shows the outline of the drive waveform of the piezoelectric element which concerns on 2nd Embodiment. It is a schematic circuit diagram which shows an example of the row control circuit which concerns on 2nd Embodiment. (A) is a timing chart showing an example of a column control signal, and (B) is a timing chart showing an example of a row signal based on the row control signal and the row control signal. 14 is a timing chart showing a change (drive waveform) of a terminal voltage of the piezoelectric element based on FIGS. 13 (A) and 13 (B). FIG. FIG. 15 is a chart showing a state of an applied voltage of a piezoelectric element corresponding to a column control signal and a row signal equivalent to those in FIGS. 13A, 13B, and 14; It is a schematic circuit diagram which shows another example of the row control circuit based on this invention.

Explanation of symbols

10 Inkjet recording device (droplet ejection device)
30 Recording head array (droplet discharge head)
32 Head unit (droplet discharge head)
60 controller (drive control means)
62, Pz _ij piezoelectric element 64 droplet ejector 66 drive control circuit (drive control means, column control means, row control means)
68 Driving IC
70 Matrix drive circuit 72, 100, 100A Row control circuit (row control means)
74 Gate switch (switching element)
76 Switch circuit (row control means)
78A Gate switch (second switching element)
78B Gate switch (first switching element)
78C Gate switch (third switching element)
L _j (L _{1 to} L ₃ ) Column control signal R _i (R _{1 to} R ₄ ) Row signal R _{i1 to} R _i3 (R _{11 to} R ₄₃ ) Row control signal

Claims (8)

A plurality of droplet ejectors that eject droplets from nozzles in accordance with a change in voltage applied to the piezoelectric element, and a droplet ejection head driving method for ejecting droplets from each of the droplet ejectors,
Provided with a plurality of switching elements capable of grounding one terminal of the piezoelectric element for each of the plurality of piezoelectric elements electrically connected in a matrix form,
A column control signal for switching on and off of the switching element is input in units of columns of the piezoelectric element, and
A row signal for switching the other terminal side of the piezoelectric element to a predetermined voltage application state, a ground state, and an open state is input in units of rows of the piezoelectric element,
Discharging a droplet from the droplet ejector by forming a voltage change between a pair of terminals of the piezoelectric element;
A method for driving a droplet discharge head. A plurality of droplet ejectors that each eject droplets from a nozzle in response to a voltage signal applied to the piezoelectric element;
When the plurality of piezoelectric elements are electrically connected in a matrix form, switching elements provided for each of the plurality of piezoelectric elements and capable of grounding one terminal of the piezoelectric elements are connected in a controllable manner in units of columns. And a matrix circuit for connecting the other terminal side of the piezoelectric element in units of rows of the piezoelectric element;
Column control means for inputting a column control signal for turning on / off the switching element in units of columns of the piezoelectric elements to the matrix circuit;
Row control means for inputting a row signal for switching the other terminal side of the piezoelectric element to the application state, the ground state, and the open state of the predetermined voltage to the matrix circuit in units of rows of the piezoelectric element;
Drive control means for controlling the output of the column control signal of the column control means and the output of the row signal of the row control means to drive each of the piezoelectric elements and eject droplets from the droplet ejector. When,
A droplet discharge apparatus comprising:   The droplet discharge apparatus according to claim 2, wherein the column control unit outputs the column control signal for turning on and off at least twice for each column within a predetermined period.   4. The droplet discharge device according to claim 2, wherein the column control unit sequentially outputs the column control signal for turning on and off the switching element in units of the columns. 5.   After the row control means switches the row signal from an open state to a ground state, a predetermined voltage application state, or an open state in synchronization with the column control signal, and holds the state for a predetermined time. The droplet discharge device according to any one of claims 2 to 4, wherein the droplet discharge device is switched to an open state.   The row control means includes a first switching element capable of outputting a predetermined voltage and a second switching element capable of grounding the output side, and the first and second switching elements are turned on separately. The liquid droplet ejection apparatus according to claim 2, wherein a row control signal to be input is input from the drive control unit.   The row control means includes a third switching element capable of outputting a voltage different from the voltage output from the first switching element, and row control signals for separately turning on the first to third switching elements are provided. The liquid droplet ejection apparatus according to claim 6, wherein the liquid droplet ejection apparatus is input from the drive control unit.   The liquid droplet according to any one of claims 2 to 7, wherein the row control means outputs a row signal for changing to the ground state and applying a voltage different from the predetermined voltage. Discharge device.

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